JavaWeb基础工具类——BaseDao-优快云博客

本文提供了一个Java程序示例，展示了如何使用JDBC连接到SQL Server数据库，并执行SQL语句进行数据检索和更新。其中包括了加载驱动、获取数据库连接、预编译SQL语句及结果集处理等关键步骤。

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 1 package dao;
 2 
 3 import java.sql.Connection;
 4 import java.sql.DriverManager;
 5 import java.sql.PreparedStatement;
 6 import java.sql.ResultSet;
 7 import java.sql.SQLException;
 8 import java.sql.Statement;
 9 
10 public class BaseDao {
11     private static String URL = "jdbc:sqlserver://localhost:1433;DatabaseName=StudentManageSys";
12     private static String USER = "sa";
13     private static String PWD = "sa";
14     protected Connection conn = null;
15     protected PreparedStatement pstmt = null;
16 
17     static {
18         try {
19             Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");
20         } catch (ClassNotFoundException e) {
21             e.printStackTrace();
22         }
23     }
24 
25     protected Connection getConnection() {
26         try {
27             return conn == null ? DriverManager.getConnection(URL, USER, PWD)
28                     : conn;
29         } catch (SQLException e) {
30             e.printStackTrace();
31             return null;
32         }
33     }
34 
35     protected void closeAll(Connection conn, Statement stmt, ResultSet rs) {
36         try {
37             if (conn != null)
38                 conn.close();
39             if (stmt != null)
40                 stmt.close();
41             if (rs != null)
42                 rs.close();
43         } catch (SQLException e) {
44             e.printStackTrace();
45         }
46     }
47 
48     protected Object execute(String sql, Object... objs) {
49         handle(sql, objs);
50         try {
51             boolean flag = pstmt.execute();
52             if (flag) {
53                 closeAll(conn, null, null);
54                 return pstmt.getResultSet();
55             } else {
56                 closeAll(conn, pstmt, null);
57                 return pstmt.getUpdateCount();
58             }
59         } catch (SQLException e) {
60             e.printStackTrace();
61             return null;
62         }
63     }
64 
65     private void handle(String sql, Object[] objs) {
66         conn = getConnection();
67         try {
68             pstmt = conn.prepareStatement(sql);
69             if (objs != null) {
70                 for (int i = 0; i < objs.length; i++) {
71                     pstmt.setObject(i + 1, objs[i]);
72                 }
73             }
74         } catch (SQLException e) {
75             e.printStackTrace();
76         }
77     }
78 }